Right now I don't see Barcelona missing the title unless they failed badly in the last 4 games because I don't see them losing the first four and El Classico will determine which team will lift the title unless Real Madrid continued trolling and losing points randomly.
There is enough games for every manager to guide his team correctly. Real Madrid has like two serious games among the remaining but I cannot say anything after what I saw from them. They should prepare well for everything and hope Barcelona miss points before them. Otherwise I agree with the percentage you mentioned for Barcelona.
Barcelona have 3 points more than Real Madrid and better goal difference, 7 points more than Atletico Madrid. They won't lose La Liga title if they only lose in a second El Clasico in this La Liga season and if they lose the El Clasico but play well in other remaining matches, they can still lift La Liga trophy.
Atletico Madrid with a late goals to beat Sevilla, took advantage of bad results from Barcelona and Real Madrid to reduce point different with two competitors, but they nearly don't have chance to win La Liga title. I believe the title race will be only between Barcelona and Real Madrid and the El Clasico result will be one of most important matches in this season late phase for deciding the champion.
Yes, that's why, Atletico Madrid who are 7 points behind, Real Madrid who are usually the favorites to win La Liga now seem very difficult to win La Liga because of their failure against Valencia which resulted in the points gap with Barcelona getting further away, which is now 4 points. So, for this season, the possibility of Barcelona becoming La Liga champions can be confirmed more than 60%, unless in the remaining matches, Barcelona experiences failure and error that continues for 3 matches. But it seems that will not happen.
Atletico Madrid fighted until last minute to beat Sevilla and they deserved the important three points. I respect their strong mentality and big dedication on fighting hard like this even they knew that they no longer have too good opportunity of winning La Liga title. This effort of Atletico Madrid contributes to excitement of La Liga in general and the title race in particular.